Regeneration of chromatographic stationary phases

ABSTRACT

Process for regenerating a chromatographic stationary phase

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of international application no.PCT/DK2004/000234, filed Apr. 2, 2004, which claims priority to Danishpatent application nos. PA 2003 00536, filed Apr. 8, 2003, and PA 200400098 filed Jan. 26, 2004 and U.S. patent application Nos. 60/462,949,filed Apr. 15, 2003 and 60/539,875 filed Jan. 27, 2004.

FIELD OF THE INVENTION

The present invention relates to the field of chromatographicpurification. More specifically it pertains to a process forregenerating chromatographic stationary phases.

BACKGROUND OF THE INVENTION

Polypeptides are increasingly being used as medicaments for thetreatment of diseases within all major therapy areas. Treatment ofdiabetes by chronic insulin administration has been practised for morethan 80 years, and therapeutic applications of polypeptides withingrowth disorders and cancer also have been practised for many years.Economical processes for the large scale production of polypeptides witha purity sufficiently high for therapeutic applications are crucial forfurther polypeptide-based therapies to reach the mass market and for theexisting therapies to become more widely used.

Purification of a polypeptide from a mixture is a step which is normallyused several times during the overall manufacturing process for atherapeutic polypeptide. Reverse phase high pressure liquidchromatography (RP-HPLC) is the preferred method for industrial highresolution separation of polypeptides, and the method has provenversatile for the large scale purification of many polypeptides.

Since polypeptides for therapeutic use are to be highly purified inorder not to cause adverse events upon administration to the patient, itis quite common to use several chromatographic purification steps in themanufacturing process. The stationary phase of chromatographic columnsin manufacturing plants are expensive and they are thus used for severalchromatographic cycles. However, over time the performance of thechromatographic stationary phase declines, i.e. pressure drop over thecolumn increases prohibitively and the separation factor is impaired.This has been attributed to the gradual build-up of deposits.

The problem has been suggested to be overcome by a regeneration processcomprising alkaline buffers (J. Chrom. 461, 1989, 45-61), e.g. pH 7.4and high concentration of organic modifier.

Brange et al. (J. Pharm. Sci. 86 (1997) 517-525) discloses dissolvinginsulin fibrils in acid and in base.

For many years the problem has been alleviated by regenerating thechromatographic stationary phase with alkaline solution, e.g. 0.1 molarsodium hydroxide (vide Liliedahl, “Twelve years of silica-based HPLCpurification with focus on peptides”, at Tides 2000, 10 May 2000 in LasVegas, USA). This regeneration process may increase the lifetime ofsilica used for purifying insulin to between 100 to 600 cycles. However,silica materials are not stable when exposed to harsh alkalineconditions, and especially substituted silica materials may not beamenable to regeneration by alkaline solutions. Economically viableprocesses for purifying pharmaceuticals such as therapeutic polypeptidesmust include a regeneration process which does not degrade thechromatographic stationary phase.

A general and complex process for regenerating particulate materials(clay, sand, silica etc.) from a wide variety of sources has beendisclosed in WO 00/61493. It is a 5 step process comprising contactingthe material with a) an extractant of organic material, b) an oxidizingagent, followed by c) an acid solution, d) heating the material and e)recovering the material. The process is cumbersome and not amenable forimplementation in a chromatographic purification plant.

There is a need in the art for more efficient ways of regeneratingchromatographic stationary phases so as to increase the lifetime ofthese expensive raw materials and prevent the pressure drop overchromatographic columns to rise. Especially, regeneration processeswhich are suited for in-situ regeneration of chromatographic stationaryphases in manufacturing plants are needed.

SUMMARY OF THE INVENTION

The present invention provides a process for regenerating achromatographic stationary phase wherein said chromatographic stationaryphase is contacted with a regeneration solution comprising at least oneorganic acid and less than about 75% w/w water.

In another aspect the present invention provides a process forregenerating a chromatographic stationary phase wherein saidchromatographic stationary phase is contacted with a regenerationsolution comprising at least one organic acid and less than about 1% w/wwater.

In one embodiment of the invention the organic acid is formic acid. Inanother embodiment of the invention the organic acid is acetic acid. Inanother embodiment the regeneration solution contains less than 0.5%water, preferably less than 0.1% water, more preferably less than 0.02%water and most preferably less than 0.001% water.

In another aspect the present invention relates to a process forregenerating a chromatographic stationary phase wherein saidchromatographic stationary phase is contacted with a regenerationsolution comprising at least one organic acid, an organic solvent andless than about 1% w/w water.

In one embodiment of the invention the organic solvent is ethanol. Inanother embodiment of the invention the organic solvent is 2-propanol.In another embodiment of the invention the organic solvent isacetonitrile. In another embodiment of the invention the organic solventis selected from the group consisting of methanol, 1-propanol, andhexylene glycol.

In another embodiment the regeneration solution contains less than 0.5%water, preferably less than 0.1% water, more preferably less than 0.02%water and most preferably less than 0.001% water.

In another aspect the present invention relates to a chromatographicstationary phase which has been regenerated by the processes of theinvention.

In another aspect the present invention relates to a polypeptide productobtained by the processes of the invention.

In yet another aspect the present invention relates to a polypeptideproduct manufactured by a process comprising the regeneration of thechromatographic stationary phase by the processes.

In yet another aspect the invention relates to an automatedchromatographic equipment comprising piping and control system forimplementing the regeneration process.

In yet another aspect the present invention relates to a pharmaceuticalcomposition prepared by purifying a polypeptide using a chromatographicstationary phase which has been regenerated by the process.

BREIF DESCRIPTION OF THE DRAWINGS

The invention is further illustrated in the appended drawings in which:

FIG. 1 shows the confocal principle.

FIG. 2 shows 2D picture of Source 30Q with insulinfibrils stained withThioflavin T.

FIG. 3 shows the principle of the measuring the area of fibrils onSource 30Q. Light coloured area shows the green light coming frominsulin fibrils on the Source 30Q particles.

FIGS. 4A-B show preparative chromatograms from chromatographicpurification III (FIG. 4A, upper figure, before regeneration with formicacid, and FIG. 4B (lower figure) after regeneration with formic acid).

DEFINITIONS

The following is a detailed definition of the terms used in thespecification.

The term “chromatographic stationary phase” as used herein means thesolid phase over which the soluble phase passes, i.e. thechromatographic matrix. The chromatographic stationary phase is normallyplaced within a chromatographic column. Examples of chromatographicstationary phases are substituted silica, such as C-4 silica, C-12silica and C-18 silica, as well as polymeric materials such aspolystyrene, Source 30Q and Sepharose. Additional examples ofchromatographic stationary phases are membranes, monolithic materialsand filters.

The term “chromatographic eluent” as used herein means the solutionwhich is used for the elution step where the polypeptide being purifiedis normally released from the chromatographic stationary phase into theeluent. In the normal mode of chromatography a complete cyclus comprises

-   -   a) equilibration with an equilibration buffer to bring the        column in a state where it is ready for a cyclus,    -   b) application of the product holding sample,    -   c) an optional washing step where the chromatographic stationary        phase with the bound product is washed,    -   d) elution where the affinity of the product towards the        chromatography stationary phase decreases and the product leaves        the column in the chromatographic column eluate, and    -   e) an optional regeneration where it is attempted to strip the        chromatographic stationary phase from remaining impurities using        a regeneration solution.

The term “equilibrium buffer” as used herein means the solution which isused for the equilibration step wherein the chromatographic column isprepared for a chromatographic cycle.

The term “regeneration solution” as used herein means a solution whichis used to regenerate a chromatographic stationary phase. The purpose ofthe regeneration is keep a satisfactory performance of thechromatographic separation over several chromatographic cycles.Typically critical performance related parameters are the pressure dropover the chromatographic column and the separation factor. Aregeneration step may comprise contacting of the chromatographicstationary phase with either a single regeneration solution or with morethan one regeneration solution. In the latter case, each of theregeneration solutions as well as the resulting mixtures of these areencompassed by the term “regeneration solution”.

The term “mixture” as used herein means a composition of mattercomprising at least two ingredients. A chromatographic column eluate isa mixture which comprises the chemicals in the eluent together with theproduct which has been stripped from the column. Another example of amixture is a solution of a chemical in a solvent, e.g. saline. Yetanother example of a mixture is water and a water-miscible organicsolvent. Yet another example of a mixture is a solution or suspension ofa polypeptide in a solvent such as water or an organic solvent

The term “isolating a polypeptide” as used herein means to bring thepolypeptide in a state where it is of higher concentration or higherpurity than it was before isolating it, i.e. in the starting material.Thus, an example of isolating a polypeptide is to precipitate orcrystallize the polypeptide from a solution and separate the precipitateor crystals from the mother liquor.

The term “organic solvent” as used herein means a solvent whichcomprises at least one carbon-atom and which is in the fluid statethroughout the temperature range from 0° C. to 50° C. Non-limitingexamples of organic solvents are lower alcohols such as methanol andethanol, polyhydric alcohols, acetonitrile, hexane and acetone.

The term “water miscible organic solvent” as used herein means anorganic solvent which has a solubility in water at 20° C. of at least 1g/L. Non-limiting examples of water miscible organic solvents areethanol, 1-propanol, 2-propanol, acetonitrile, and hexyleneglycol.

The term “organic acid” as used herein means an organic compound whichhas at least one functional group with a dissociation constant, pK_(a),of less than 5.0. Examples of organic acids are formic acid, aceticacid, citric acid etc.

The term “lower alcohol” as used herein means a C₁₋₆-alcohol which ischaracterized by having between 1 and 6 carbon atoms and one hydroxylmoiety. The carbon skeleton in the lower alcohol may be straight orbranched. Non-limiting examples of lower alcohols are ethanol,n-propanol, iso-propanol, and t-butanol.

The term “polyhydric alcohol” as used herein means an alcohol having atleast two hydroxyl moieties. Non-limiting examples of polyhydricalcohols are hexylene glycol (4-methyl-2,4-pentanediol) and neopentylalcohol (2,2-dimethyl-1,3-propanediol).

The term “excipient” as used herein means compounds which are added topharmaceutical compositions in order to stabilize and preserve thecomposition. Typical excipients are buffers, preservatives and tonicitymodifiers.

The term “pharmaceutical composition” as used herein means a productcomprising an active compound or a salt thereof together withpharmaceutical excipients such as buffer, preservative and tonicitymodifier, said pharmaceutical composition being useful for treating adisease or disorder. Thus a pharmaceutical composition is also known inthe art as a pharmaceutical formulation.

The term “buffer” as used herein refers to a chemical compound which isused in a solution to reduce the tendency of pH of the solution tochange over time as would otherwise occur due to chemical reactions.Buffers include chemicals such as sodium phosphate, TRIS, glycine andsodium citrate.

The term “tonicity modifier” as used herein refers to a chemicalcompound in a pharmaceutical composition that serves to modify theosmotic pressure of the pharmaceutical composition so that the osmoticpressure becomes closer to that of human plasma. Tonicity modifiersinclude NaCl, glycerol, D-mannitol etc.

The term “pharmaceutically acceptable” as used herein means suited fornormal pharmaceutical applications, i.e. does not cause adverse eventsin patients etc.

The term “human insulin” as used herein means the human hormone whosestructure and properties are well known. Human insulin has twopolypeptide chains that are connected by disulphide bridges betweencysteine residues, namely the A-chain and the B-chain. The A-chain is a21 amino acid peptide and the B-chain is a 30 amino acid peptide, thetwo chains being connected by three disulphide bridges: one between thecysteines in position 6 and 11 of the A-chain, the second between thecysteine in position 7 of the A-chain and the cysteine in position 7 ofthe B-chain, and the third between the cysteine in position 20 of theA-chain and the cysteine in position 19 of the B-chain.

The term “polypeptide” as used herein means a compound composed of atleast ten constituent amino acids connected by peptide bonds. Theconstituent amino acids may be from the group of the amino acids encodedby the genetic code and they may natural amino acids which are notencoded by the genetic code, as well as synthetic amino acids. Naturalamino acids which are not encoded by the genetic code are e.g.hydroxyproline, γ-carboxyglutamate, ornithine, phosphoserine, D-alanineand D-glutamine. Synthetic amino acids comprise amino acids manufacturedby chemical synthesis, i.e. D-isomers of the amino acids encoded by thegenetic code such as D-alanine and D-leucine, Aib (α-aminoisobutyricacid), Abu (α-aminobutyric acid), Tle (tert-butylglycine); andβ-alanine.

The term “therapeutic polypeptide” as used herein means a polypeptidefor which there is a recognized potential utility as a therapeuticagent. Therapeutic polypeptides are typically highly purified and theyare subjected to clinical studies as part of the regulatory approvalprocess. Examples of therapeutic polypeptides are human insulin,thrombopoetin, erythropoietin and human growth hormone.

The term “polypeptide product” as used herein means a compositioncomprising the polypeptide. Examples of polypeptide products arecrystallized polypeptide, precipitated polypeptide, and a solution ofthe polypeptide.

The term “analogue” as used herein in relation to a parent polypeptidemeans a modified polypeptide wherein one or more amino acid residues ofthe parent polypeptide have been substituted by other amino acidresidues and/or wherein one or more amino acid residues have beendeleted from the parent polypeptide and/or wherein one or more aminoacid residues have been deleted from the parent polypeptide and/orwherein one or more amino acid residues have been added to the parentpolypeptide. Such addition or deletion of amino acid residues can takeplace at the N-terminal of the polypeptide or at the C-terminal of thepolypeptide or within the polypeptide. An example of an analogue isArg³⁴-GLP-1 (7-37) which is a GLP-1(7-37) polypeptide wherein the Lys atposition 34 has been replaced with an Arg. Other examples are porcine orbovine insulin which are both analogues of human insulin.

The term “precursor” as used herein in relation to a polypeptide means amodified version of the polypeptide which is being produced. Precursorsof a polypeptide are typically amino acid extended versions of thepolypeptide, or truncated versions of the polypeptide. These precursormay serve to enhance cellular expression, comprise affinity tags forpurification, protect certain reactive groups of the polypeptide beingproduced, etc.

The term “derivative” as used herein in relation to a parent polypeptidemeans a chemically modified parent polypeptide or an analogue thereof,wherein at least one substituent is not present in the parentpolypeptide or an analogue thereof, i.e. a parent polypeptide which hasbeen covalently modified. Typical modifications are amides,carbohydrates, alkyl groups, acyl groups, esters, PEGylations and thelike. Examples of derivatives of human insulin are threonine methylester^(B30) human insulin and N^(εB29)-tetradecanoyl des(B30) humaninsulin.

The term “lipophilic substituent” as used herein means a substituentcomprising 4-40 carbon atoms and having a solubility in water at 20° C.in the range from about 0.1 mg/100 ml water to about 250 mg/100 mlwater, such as in the range from about 0.3 mg/100 ml water to about 75mg/100 ml water. For instance, octanoic acid (C8) has a solubility inwater at 20° C. of 68 mg/100 ml, decanoic acid (C10) has a solubility inwater at 20° C. of 15 mg/100 ml, and octadecanoic acid (C18) has asolubility in water at 20° C. of 0.3 mg/100 ml.

The term “piping and control system” as used herein means the physicalmeans (pipes and control valves) and the software controlling the pipesand valves of a process equipment.

DESCRIPTION OF THE INVENTION

The present invention is concerned with a process for regenerating achromatographic stationary phase wherein said chromatographic stationaryphase is contacted with a regeneration solution comprising at least oneorganic acid and less than about 75% w/w water. The present invention isalso concerned with a process for regenerating a chromatographicstationary phase wherein said chromatographic stationary phase iscontacted with a regeneration solution comprising at least one organicacid and less than about 1% w/w water.

The present invention is also concerned with a process for regeneratinga chromatographic stationary phase wherein said chromatographicstationary phase is contacted with a regeneration solution having aconcentration of organic acid which is at least 25% w/w. A number oforganic acids may be used in the regeneration solution of the process. Apreferred organic acid is formic acid. Another organic acid for theregeneration solution is acetic acid. Another regeneration solutioncomprises two organic acids, e.g. formic acid and acetic acid.

The regeneration solution may furthermore comprise an organic solvent.Preferably the organic solvent is also used in the equilibrium buffer orchromatographic eluent. In one embodiment of the invention the organicsolvent is ethanol. In another embodiment the organic solvent is2-propanol. In another embodiment the organic solvent is acetonitrile.In another embodiment the organic solvent is selected from the groupconsisting of methanol, 1-propanol and hexylene glycol.

In another embodiment, the organic acid is formic acid and the organicsolvent is ethanol. In another embodiment, the organic acid is formicacid and the organic solvent is acetonitrile. In yet another embodiment,the organic acid is formic acid and the organic solvent is 2-propanol.In yet another embodiment, the organic acid is formic acid and theorganic solvent is hexylene glycol. In another embodiment, the organicacid is acetic acid and the organic solvent is ethanol. In anotherembodiment, the organic acid is acetic acid and the organic solvent isacetonitrile. In yet another embodiment, the organic acid is acetic acidand the organic solvent is 2-propanol. In yet another embodiment, theorganic acid is acetic acid and the organic solvent is hexylene glycol.

In another embodiment, the present invention relates to a process forregenerating a chromatographic stationary phase wherein saidchromatographic stationary phase is contacted with a regenerationsolution comprising at least one organic acid and less than 0.5% water,preferably less than 0.1% water, more preferably less than 0.02% waterand most preferably less than 0.001% water.

The chromatographic stationary phase is preferably contacted with theregeneration solution inside the chromatographic column. In this way aminimum of production capacity is lost due to down-time in connectionwith the regeneration step. Thus, the process of regenerating thechromatographic stationary phase can be performed without repacking thecolumn. In one embodiment, the chromatographic stationary phase isfluidized during said regeneration. In another embodiment thechromatographic eluent or equilibrium buffer is displaced by a watermiscible organic solvent before said chromatographic stationary phase iscontacted with said regeneration solution. Preferably said watermiscible organic solvent is also present in the chromatographic eluentor equilibrium buffer. Preferably said water miscible organic solvent isalso present in the regeneration solution.

In another embodiment the chromatographic stationary phase is contactedwith said regeneration solution outside the chromatographic column. Thisprocedure is more cumbersome than performing the regeneration processinside the column, but it may nevertheless be useful if precipitatedmaterial is trapped between the chromatographic stationary phaseparticle. In the latter case, the precipitated material can be removedfrom the chromatographic stationary phase without dissolving saidmaterial.

In one embodiment the chromatographic stationary phase is a RP-HPLCmatrix. The chromatographic stationary phase for RP-HPLC aremechanically very rigid materials which may be silica or substitutedsilica such as C4, C6, C8, C10, C12, C16, C18, C30 or phenyl silica, orit may be a pressure stable polymeric material which is substituted orunsubstituted. The chromatographic stationary phase, be it a silicabased matrix or a polymeric material, may also be present in the columnsas monolithic rods with macropores and mesopores.

Suitable silica material for use as chromatographic stationary phase isspherical particles with a narrow pore size distribution and particlesizes in the range from 3 μm to 100 μm, such as from 5 μm to 100 μm,such as from 8 μm to 30 μm, such as 10 μm, 13 μm, 15 μm, 16 μm, 18 μmand 20 μm. Typically pore sizes in the range of 60 Å to 300 Å, such as100 Å, 120 Å, 150 Å, 175 Å, 200 Å or 300 Å, are used. For pressurestable polymeric materials the pore size may be from 10 Å or evenhigher, e.g. 50 Å, 100 Å, 400 Å, 600 Å, 1000 Å or 3000 Å. In oneembodiment the pressure stable polymeric material is Source 30Q or XAD1180. The chromatographic column is packed with the stationary phase andafter appropriate testing of the quality of the packing, the column isequilibrated with the buffer used in the binding mode. Production scalechromatographic columns typically have diameters of 15 to 100 cm, andsuch systems may have dynamic axial compression. For production of smallvolume polypeptides the production columns may have a diameter of e.g.15 cm, 20 cm or 25 cm. For production of large volume polypeptides theproduction columns may have a diameter of e.g. 40 cm, 60 cm, 80 cm orlarger.

In another embodiment of the invention, the chromatographic stationaryphase being regenerated is a membrane, monolithic materials, filters orthe like.

In one embodiment of the process for regenerating a chromatographicstationary phase, said chromatographic stationary phase is contactedwith said regeneration solution for at least 1 second, preferably for atleast 1 minute, more preferably for at least 5 minutes, such as from 1minute to 24 hours, from 1 minute to 5 hours, from 1 minute to 2 hours,from 10 minutes to 60 minutes.

In another embodiment of the process for regenerating a chromatographicstationary phase, said chromatographic stationary phase is contactedwith said regeneration solution until the pressure drop over the lengthof the chromatographic column at normal flow rate decreases by at least10%, preferably at least 25%, even more preferably at least 50%.

In another embodiment of the process for regenerating a chromatographicstationary phase, contacting of said chromatographic stationary phasewith the regeneration solution is performed at a temperature in therange from about 0° C. to 70° C., from 5° C. to 50° C., such as from 10°C. to 40° C., such as from 15° C. to 30° C., or from 18° C. to 25° C.

In another embodiment of the process for regenerating a chromatographicstationary phase, the life time of said chromatographic stationary phaseis at least 500 chromatographic cycles, preferably at least 700chromatographic cycles, more preferably at least 1000 chromatographiccycles, most preferably at least 2000 chromatographic cycles.

In another embodiment of the process for regenerating a chromatographicstationary phase, said process is applied to said chromatographicstationary phase for every chromatographic cycle, at least once every 2chromatographic cycles, at least once every 5 chromatographic cycles, atleast once every 20 chromatographic cycles, at least once every 50chromatographic cycles, or at least once every 100 chromatographiccycles.

In another embodiment of the invention, the number of regenerationprocesses performed on a chromatographic stationary phase is at least25, at least 50, at least 100, at least 200, at least 400 or at least1000.

In another embodiment of the process for regenerating a chromatographicstationary phase, said process is applied to said chromatographicstationary phase whenever the pressure drop over the length of thechromatographic column exceeds a threshold value.

Another aspect of the present invention is a process for the productionof a therapeutic polypeptide or a precursor thereof, said processcomprising at least one chromatographic step wherein the chromatographicstationary phase is regenerated by a regeneration process as describedabove. In one embodiment of the process for the production of atherapeutic polypeptide or a precursor thereof, said therapeuticpolypeptide is a derivative comprising a lipophilic substituent. Inanother embodiment of the process for the production of a therapeuticpolypeptide or a precursor thereof, said therapeutic polypeptide is aderivative comprising a lipophilic substituent attached to the ε-aminogroup of a lysine residue. In another embodiment of the process for theproduction of a therapeutic polypeptide or a precursor thereof, saidtherapeutic polypeptide is selected from the group consisting ofglucagon, glucagon-like peptide 1, glucagon-like peptide 2, exendin-4,TFF peptides, human insulin, analogues thereof and derivatives thereof.In another embodiment said polypeptide is selected from the groupconsisting of Lys²⁶(N^(ε)-(γ-Glu(N^(α)-hexadecanoyl)))-GLP-1(7-37),Arg³⁴-GLP-1(7-37), exendin-4, Lys ¹⁷Arg³⁰-GLP-2(1-33), Arg³⁰Lys¹⁷N^(ε)(β-Ala(N^(α)-hexadecanoyl)) GLP-2(1-33) and Gly²-GLP-2(1-33). Inanother embodiment said polypeptide is exendin-4. In another embodimentsaid polypeptide is a fusion polypeptide comprising human serum albuminor a fragment thereof. In another embodiment said polypeptide is afusion polypeptide between GLP-1(7-37) or an analogue thereof and ahuman serum albumin fragment or an analogue thereof. In anotherembodiment said polypeptide is a fusion polypeptide betweenexendin-4(1-39) or an analogue thereof and a human serum albuminfragment or an analogue thereof. In another embodiment said polypeptideis a fusion polypeptide comprising the Fc portion of an immunoglobulinor a fragment thereof. In another embodiment said polypeptide is afusion polypeptide between GLP-1 (7-37) or an analogue thereof and afragment of the Fc portion of an immunoglobulin or an analogue thereof.In another embodiment said polypeptide is a fusion polypeptide betweenexendin-4(1-39) or an analogue thereof and a fragment of the Fc portionof an immunoglobulin or an analogue thereof.

In another embodiment said polypeptide is selected from the groupconsisting of human insulin, a human insulin precursor, a human insulinanalog, a human insulin analog precursor, a GLP-1(7-37) analogue, anexendin-4(1-39) analogue, and derivatives thereof. In another embodimentsaid polypeptide is selected from a human insulin derivative comprisingat least one methoxy or ethoxy moiety. In another embodiment saidpolypeptide is selected from the group consisting of

-   threonine methyl ester^(B30) human insulin,-   threonine ethyl ester^(B30) human insulin,-   Asp^(B28) human insulin,-   threonine methyl ester^(B30) Asp^(B28) human insulin,-   threonine ethyl ester^(B30) Asp^(B28) human insulin,-   LyS^(B28) Pro^(B29) human insulin,-   Met^(B-1)Arg^(B0)Lys^(B28) Pro^(B29) human proinsulin,-   Lys^(B3) Glu^(B29) human insulin,-   Gly^(A21) Arg^(B31) Arg^(B32) human insulin,-   des(B30) human insulin,-   N^(εB29)-tetradecanoyl des(B30) human insulin,-   N^(εB29)-litocholoyl-γ-glutamyl des(B30) human insulin,-   N^(εB29)-octanoyl des(B30) human insulin, and.-   N^(εB29)-octanoyl human insulin.

In yet another embodiment said polypeptide is selected from human serumalbumin, erythropoietin, TNF-α, an interleukin, IGF-1, IGF-2, humangrowth hormone, somatostatin, human amylin and analogues thereof.

The polypeptides being purified on chromatographic stationary phasesregenerated by the processes of the present invention may be produced bya variety of techniques known in the art of polypeptide production.Polypeptides larger than 3000 Dalton are usually produced byfermentation or cell culture, whereas smaller polypeptide may beproduced by chemical peptide synthesis. Other important factorsdetermining the optimal production method are also the amount ofpolypeptide to be produced and the structure of the polypeptide, e.g.disulphide bonds and other modifications. Fermentation or cell culturederived polypeptides are commonly produced by cultivation of recombinanthost cells, e.g. bacteria, fungi mammalian cells, insect cells or plantcells in appropriate cultivation media. The cultivation medium may be amore or less chemically defined medium containing the necessarynutrients for growth and product formation of the host cells, e.g.sugar, nitrogen source, salts, vitamins and other growth factors. Oncethe microorganisms or the cells have been cultivated in the medium andthey have optionally been disrupted, the cultivation medium contains thedesired product in a mixture with remnant medium components, host cellderived impurities and product related impurities. Host cell derivedimpurities are mainly polypeptides, nucleic acids and cellular debris.The product is separated from these non-related impurities in therecovery or early purification steps. In the final purification steps(polishing) where impurities closely related to the product polypeptideare separated from the product polypeptide, chromatographic steps areextensively used.

Synthesis of polypeptides may also be performed via solid phasesynthesis by Merrifield-type chemistry, by solution phase methods, or bysemisynthetic methods known in the art.

One or more chemical conversion steps may be performed in-between therecovery and the final purification steps. Such chemical modificationsmay by the hydrolysis of a precursor polypeptide wherein the amino acidextension on the polypeptide is cleaved of the polypeptide. Such aminoacid extensions may be used for increasing the host cell expression inthe case of culture derived polypeptides, or it may be used tospecifically purify the polypeptide, such as by affinity chromatographye.g. IMAC purification of histidine tagged polypeptides. The chemicalconversion can also be the chemical modification to produce apolypeptide which is a derivative, e.g. by acylation, PEGylation oresterification. Such chemical modifications are well known in the art(see e.g. WO 98/08871, WO 99/43706, U.S. Pat. No. 5,424,286, WO00/09666, WO 00/66629, WO 01/04156 and WO 02/90388).

Another aspect of the present invention is the use of the aboveprocesses for regenerating a chromatographic stationary phase fordecreasing the pressure drop over the length of the chromatographiccolumn.

Another aspect of the present invention is the use of the aboveprocesses for regenerating a chromatographic stationary phase for themanufacture of a therapeutic polypeptide.

Another aspect of the present invention is a chromatographic stationaryphase which has been regenerated by contacting said chromatographicstationary phase with a regeneration solution, said regenerationsolution comprising at least one organic acid and less than about 75%w/w water. Another aspect of the present invention is a chromatographicstationary phase which has been regenerated by contacting saidchromatographic stationary phase with a regeneration solution, saidregeneration solution comprising at least one organic acid and less thanabout 1% w/w water.

In one embodiment the chromatographic stationary phase has beenregenerated by a process as described above. In another embodiment thechromatographic stationary phase has been regenerated by a process,wherein said regeneration solution contains less than 0.5% water,preferably less than 0.1% water, more preferably less than 0.02% waterand most preferably less than 0.001% water. In a further embodiment theregenerated chromatographic stationary phase is a silica, or asubstituted silica material.

In another aspect the present invention relates to a polypeptide productmanufactured by a process comprising the steps of

-   -   a) purifying a polypeptide or a precursor thereof using the        chromatographic stationary phase produced by the regeneration        process of the present invention, and    -   b) isolating said polypeptide or a precursor thereof to give the        resulting polypeptide product.

In another aspect the present invention relates to a polypeptide productmanufactured by a process wherein is used a chromatographic stationaryphase regenerated according to the process of the present invention.

In another aspect the present invention relates to an automatedchromatographic equipment comprising piping and control system forimplementing the regeneration process according to the presentinvention.

In another aspect the present invention relates to a pharmaceuticalcomposition prepared by a process comprising the steps of

-   -   a) first purifying a polypeptide or a precursor thereof using a        chromatographic stationary phase regenerated by the process        according to the present invention,    -   b) then drying said polypeptide, and    -   c) finally admixing with a pharmaceutically acceptable        excipient.

In another aspect the present invention relates to a pharmaceuticalcomposition prepared by a process comprising the steps of

-   -   a) first purifying a polypeptide or a precursor thereof using a        chromatographic stationary phase regenerated by the process        wherein said chromatographic stationary phase is contacted with        a regeneration solution comprising at least one organic acid and        less than 0.5% water, preferably less than 0.1% water, more        preferably less than 0.02% water and most preferably less than        0.001% water, and    -   b) then drying said polypeptide, and    -   c) finally admixing with a pharmaceutically acceptable        excipient.

EXAMPLES

The following acronyms for commercially available chemicals andmaterials are used:

-   HCOOH: Formic acid-   EtOH: Ethanol-   AcOH: Acetic acid-   ODDMS: Octadecyldimethyl substituted silica particles (ODDMS silica)

The formic acid used for examples 1-68, 70-71, 73-74 and 76 has aspecified purity of 98-100% (according to manufacturer), and the formicacid used for example 72 has a purity of 99.9%.

The abbreviation CV means Column Volumes as known in the field ofchromatography.

Example 1-68

The over all set-up of the experiments of example 1-68 was as follows:

-   -   1) Determination of the back pressure and height of valley of a        column with no pressure problems (a new unused column).    -   2) Introduction of pressure and performance problems.    -   3) Determination of the back pressure and height of valley of a        column with pressure problems.    -   4) Regeneration of the column.    -   5) Determination of the back pressure and height of valley of a        column after regeneration.        Determination of the Back Pressure and Height of Valley:

The same type of silica gel was used for all the experiments mentionedin this section. The silica gel is an ODDMS 200 Å, 15 μm silica gel.Mostly, the same gel batch (batch no. 205144) was used (all the columnsstarting with 874-).

The silica gel was packed in 10 mm×250 mm steel columns and tested in afunctionality test using DesB30 insulin as the test substance andeluting with water-ethanol mixtures containing calcium chloride andpotassium chloride salts (see table 1). The back pressure under elutionand the height of valley between DesB30 insulin and the nearest impurity(in front of the insulin peak) were used as the test parameters for howwell the column had regained its performance.

The elution time of DesB30insulin may be subject to some experimentalvariation due to small variations in temperature and other experimentalparameters. When the elution time of DesB30insulin is the same indifferent experiments the height of valley is a perfect comparison ofthe columns separation performance. When the elution time ofDesB30insulin varies between experiments the height of vallay is a lessgood measure of the column separation performance. All else equal, thelonger the retention time is the lower the height of valley will be.TABLE 1 Solutions used in the functionality test. Inlet Buffer TypeContent (w/w) A11 1 Equlibration buffer 20% ethanol A12 2 Elution bufferA 25% ethanol, 1.5% KCl, 0.4% CaCl₂ and 0.15% triethanol amine (pH 7.4with HCl) B1 3 Elution buffer B 35% ethanol, 1.5% KCl, 0.4% CaCl₂ and0.15% triethanol amine (pH 7.4 with HCl) A13 4 Regeneration 70% ethanoland 6.9% acetic acid buffer A18 Application DesB30 insulin Na₂EDTAsolution, pH 7.5, ethanol

The functionality test was performed at 23±2° C. on an Äktaexplorer 100Awith Unicorn 4.0 as the control software and running the followingcolumn cycle (se table 2): TABLE 2 Column cycle in the functionalitytest (CV is column volumes). Action CV (no.) Volume (ml) Equilibration 358.9 Loading 0.8 15 Wash 1 1 19.6 Elution 10 196.3 Wash 2 0.5 9.8 Rinse2 39.3

A column packed with silica gel (batch 205144) was tested and the backpressure measured to 3.4±0.1 MPa. Similarly the back pressure wasdetermined for other columns before introducing pressure problems.Experiments show that if these values are regained after treatment, thecolumn has regained its performance.

The height of valley was also determined for the individual columnsbefore and after introduction of pressure and performance problems, andafter regeneration of the column.

Introduction of Pressure and Performance Problems:

Pressure and performance problems were introduced in 1 of 3 ways:

-   -   1) The column was used in the functionality test but was taken        off the system after loading and placed at 70° C. for 1-16        hours. Thereafter the back pressure and height of valley were        measured performing the rest of the functionality test.    -   2) The ODDMS silica gel (25 g) was stirred in a beaker with        DesB30 insulin (0.14 g), 0.1 M Tris buffer (22 ml) and ethanol        (15 ml) at 50° C. for 1 hour. Thereafter the gel was decanted        and packed in a steel column (10 mm×250 mm). The backpressure        and height of valley were measured performing the functionality        test. This method can also be performed at lower temperatures        but that demands longer reaction times.    -   3) A combination of 1) and 2). Firstly, the gel was treated as        in 2) but after packing, the column was treated as in 1).

The methods used for the individual columns are listed in table 4 below.

Regeneration of the Column (e.i. Removal of Pressure and PerformanceProblems):

The regeneration of the column was also performed on the Äktaexplorer100. The column cycle for this process can be seen in table 3 below.After regeneration, the column was again tested in the functionalitytest and the back pressure determined. TABLE 3 Column cycle underregeneration. Action Solvent CV (no.) Volume (ml) Wash 1 EtOH 3 58.9Regeneration See table 4 and 5 2 39.3 Left to stand — 0 30 minutesRegeneration See table 4 and 5 2 39.3 Wash 2 EtOH 3 58.9

Different solvents were testet at 22° C. and 40° C. (the entire HPLCsystem was placed in a refrigerator at the chosen temperature ±1° C.).The specific conditions for the individual columns are shown in table 4and the results from the functionality tests are shown in table 5.

Specific Experimental Conditions for the Individual Columns: TABLE 4Experimental conditions for individual columns. Ex- Introduction Tem-am- of problems pera- ple Column by ture no. no. method no. Regenerationsolvent (° C.) 1 204377/1 1 HCOOH 22 2 874-32/1 2 HCOOH 22 3 874-32/2 3HCOOH 22 4 874-32/7 2 HCOOH 22 5 874-33/9 2 HCOOH 22 6 874-33/6 3 HCOOH22 7 874-24/22 2 HCOOH 40 8 874-24/10 3 AcOH 22 9 874-24/15 2 AcOH 22 10874-24/23 2 AcOH 40 11 874-31/1 2 AcOH 40 12 203635/5 1 HCOOH/AcOH 99:122 13 874-24/6 3 HCOOH/AcOH 99:1 22 14 205019/1 1 HCOOH/AcOH 99:1 40 15204770/1 1 HCOOH/AcOH 3:1 22 16 874-24/26 2 HCOOH/AcOH 3:1 40 17204888/1 1 HCOOH/AcOH 1:1 22 18 874-24/27 2 HCOOH/AcOH 1:1 40 19204923/1 1 HCOOH/AcOH 1:3 22 20 874-24/28 2 HCOOH/AcOH 1:3 40 21203251/3 1 HCOOH/EtOH 99:1 22 22 874-24/4 2 HCOOH/EtOH 99:1 22 23204815/1 1 HCOOH/EtOH 99:1 40 24 204815/1 1 HCOOH/EtOH 3:1 22 25204888/1 1 HCOOH/EtOH 3:1 40 26 874-24/5 3 HCOOH/EtOH 1:1 22 27874-24/16 2 HCOOH/EtOH 1:1 22 28 204923/1 1 HCOOH/EtOH 1:1 40 29204550/1 1 HCOOH/EtOH 1:3 22 30 874-24/17 2 HCOOH/EtOH 1:3 22 31204770/1 1 HCOOH/EtOH 1:3 40 32 203635/5 1 HCOOH/water 99:1 22 33874-24/24 2 HCOOH/water 99:1 40 34 204377/1 1 HCOOH/water 95:5 22 35874-24/29 2 HCOOH/water 95:5 40 36 202985/2 1 HCOOH/water 4:1 22 37874-24/30 2 HCOOH/water 4:1 40 38 204550/1 1 HCOOH/water 1:1 22 39874-24/31 2 HCOOH/water 1:1 40 40 874-33/5 3 HCOOH/water 1:1 40 41874-24/7 3 HCOOH/water 1:3 22 42 874-24/18 2 HCOOH/water 1:3 22 43204770/1 1 HCOOH/water 1:3 40 44 874-24/8 3 AcOH/water 99:1 22 45874-24/19 2 AcOH/water 99:1 40 46 874-24/11 3 AcOH/water 3:1 22 47874-24/20 2 AcOH/water 3:1 40 48 874-31/2 2 AcOH/water 3:1 40 49874-33/4 3 AcOH/water 3:1 40 50 874-24/12 3 AcOH/water 1:1 22 51874-24/25 2 AcOH/water 1:1 40 52 874-31/3 2 AcOH/water 1:1 40 53874-24/13 3 HCOOH/phenol/water 22 1:1:1 54 874-24/21 2HCOOH/phenol/water 22 1:1:1 55 874-32/3 2 1500 ppm Na- 22 hypochlorite56 874-33/11 3 1500 ppm Na- 22 hypochlorite 57 874-33/14 2 1500 ppm Na-22 hypochlorite 58 874-32/4 2 Performic acid 22 59 874-33/13 3 Performicacid 22 60 874-33/18 2 Performic acid 22 61 874-32/5 2 1.5M formaldehyde22 62 874-33/12 3 1.5M formaldehyde 22 63 874-33/15 2 1.5M formaldehyde22 64 874-32/6 2 6M guanidine 22 hydrochloride 65 874-33/10 3 6Mguanidine hydrochloride 22 66 874-33/17 2 6M guanidine hydrochloride 2267 874-33/19 2 EtOH (60% w/w)/0.1M 22 NaOH 68 874-33/20 3 EtOH (60%w/w)/0.1M 22 NaOH

Functionality Test Results for the Individual Columns: TABLE 5 Backpressure and height of valley results from functionality tests performedbefore and after introduction of problems and after regeneration of thecolumns according to the conditions listed in table 4. RT is theretention time for DesB30 insulin and height of valley (HV) is forDesB30 insulin and the nearest impurity. Performance Before After AfterBack pressure (MPa) problems problems regeneration Example Before AfterHV RT HV RT HV no. problems problems After regeneration RT ml mAU ml mAUml mAU 1 3.8 6.2 3.8 140.2 38.4 144.3 36.1 2 3.4 5.8 3.6 141.2 39.6146.6 62.0 138.6 44.5 3 3.4 >10 3.7 141.2 39.6 — — 137.9 45.9 4 3.4 4.43.4 141.2 39.6 146.6 62.0 139.0 43.2 5 3.4 4.7 3.4 141.7 41.9 134.6 63.0139.2 42.9 6 3.4 >10 3.6 141.7 41.9 — — 140.1 45.8 7 3.4 4.7 3.4 134.554.3 136.5 47.8 137.2 48.6 8 3.4 >10 >10 134.5 54.3 — — — — 9 3.4 4.74.4 134.5 54.3 136.5 47.8 135.9 48.4 10 3.4 4.7 3.9 134.5 54.3 136.547.8 135.0 50.1 11 3.4 4.2 4.2 134.5 54.3 149.5 44.7 12 3.0 3.7 2.8136.1 42.7 130.3 51.9 13 3.4 >10 3.5 134.5 54.3 — — 145.2 44.4 143.5 >10 3.5 139.9 44.1 — — 135.9 44.8 15 3.5 >10 3.3 138.7 40.6 — —127.3 54.7 16 3.4 4.7 3.4 134.5 54.3 136.5 47.8 139.3 45.0 17 3.0 >102.9 139.2 30.4 — — 130.2 36.2 18 3.4 4.7 3.4 134.5 54.3 136.5 47.8 137.147.0 19 3.1 >10 3.0 130.2 36.2 — — 133.3 57.2 20 3.4 4.7 3.5 134.5 54.3136.5 47.8 136.6 47.5 21 2.2 3.4 2.3 131.6 32.9 133.8 35.2 22 3.4 5.23.4 134.5 54.3 136.5 47.8 135.1 50.1 23 3.4 5.8 3.3 148.5 29.6 142.065.0 24 3.3 6.2 3.1 135.2 35.4 135.3 34.0 25 3.1 9 3.1 157.0 24.7 — —151.3 31.9 26 3.4 >10 >10 134.5 54.3 — — — — 27 3.4 4.7 3.5 134.5 54.3136.5 47.8 136.2 46.9 28 3.2 >10 3.5 139.7 44.7 — — 148.0 35.7 292.8 >10 >10 142.4 23.2 — — — — 30 3.4 4.7 4.1 134.5 54.3 136.5 47.8137.6 44.2 31 3.6 >10 >10 147.4 38.7 — — — — 32 3.1 6.9 3.1 143.8 34.7136.3 41.4 33 3.4 4.7 3.3 134.5 54.3 136.5 47.8 132.1 55.8 34 3.7 >103.9 140.6 41.6 — — 145.8 34.5 35 3.4 4.7 3.6 134.5 54.3 136.5 47.8 139.842.0 36 2.4 5.1 2.3 145.8 22.0 134.1 32.0 37 3.4 4.7 3.5 134.5 54.3136.5 47.8 140.3 45.4 38 2.6 4.6 2.7 126.6 27.2 135.9 34.5 39 3.4 4.73.4 134.5 54.3 136.5 47.8 140.4 42.2 40 3.4 >10 4.1 141.7 41.9 — — 141.864.0 41 3.4 >10 >10 134.5 54.3 — — — — 42 3.4 4.7 3.3 134.5 54.3 136.547.8 137.0 45.6 43 3.4 5.8 3.8 131.9 47.0 145.0 40.8 44 3.4 >10 >10134.5 54.3 — — — — 45 3.4 4.7 4.3 134.5 54.3 136.5 47.8 135.2 42.9 463.4 >10 5.2 134.5 54.3 — — 134.2 119.3  47 3.4 4.7 3.4 134.5 54.3 136.547.8 134.4 64.0 48 3.4 4.2 3.5 134.5 54.3 137.3 47.7 49 3.4 >10 5.6141.7 41.9 — — 141.9 73.4 50 3.4 >10 9 134.5 54.3 136.5 47.8 — — 51 3.44.7 3.4 134.5 54.3 136.5 47.8 134.9 50.7 52 3.4 4.2 3.5 134.5 54.3 126.962.7 53 3.4 >10 4.1 134.5 54.3 — — 137.7 46.1 54 3.4 4.7 3.4 134.5 54.3136.5 47.8 138.6 45.0 55 3.4 4.4 3.8 141.2 39.6 146.6 62.0 138.0 46.2 563.4 >10 >10 141.7 41.9 — — — — 57 3.4 4.7 4.1 141.7 41.9 134.6 63.0149.8 39.3 58 3.4 4.4 3.6 141.2 39.6 146.6 62.0 138.2 46.1 59 3.4 >103.5 141.7 41.9 — — 135.5 52.3 60 3.4 4.7 3.3 141.7 41.9 134.6 63.0 135.154.1 61 3.4 4.4 3.7 141.2 39.6 146.6 62.0 137.7 49.4 62 3.4 >10 >10141.7 41.9 — — — — 63 3.4 4.7 3.9 141.7 41.9 134.6 63.0 147.6 40.7 643.4 4.4 3.5 141.2 39.6 146.6 62.0 139.4 45.0 65 3.4 >10 >10 141.7 41.9 —— — — 66 3.4 4.7 3.8 141.7 41.9 134.6 63.0 137.4 53.4 67 3.4 4.7 3.5141.7 41.9 134.6 63.0 138.4 39.1 68 3.4 >10 3.9 141.7 41.9 134.6 — 138.849.3

Example 69

Column Life Time—Chromatographic Solvents/Eluents.

The life time of substituted silica gels may be limited by the chemicaldegradations of the gel by the solutions applied to the chromatographiccolumn, e.g. buffers and regeneration solutions. Chemical degradation ofsubstituted silica gels may be observed by the appearance of silicium inthe exit from the column, or by lowering of the carbon contents of thegel showing loss of the substitution. The following experiments show thesilicium appearance in column effluent and the decrease of the carboncontents of the gels during prolonged flushing with threechromatographic solutions: 20% ethanol in water, eluent 1 and eluent 2.Composition of eluent 2 is 31% w/w ethanol, 1.5% w/w KCl, 0.40% w/wCaCl₂, 0.15% w/w triethanol amine and pH adjusted to pH 7.4 using HCl.The composition of eluent 1 is salt, buffer, ethanol and pH 3.0.

A batch of ODDMS silica gel was packed in five 4.0×250 mm steel columnsby standard procedure for packing chromatographic columns. The columnswere then equilibrated with 3 CV of ethanol before continuous flushingwith a chromatographic eluent was started. The five columns were thenflushed with a chromatographic eluent (20% EtOH, eluent 1 or eluent 2)for 1, 3, 7, 12, and 16 days, respectively. After the appropriateflushing time each column were then equilibrated with 3 CV of ethanoland the silica gel was taken out of the columns. A sample of the spentsilica gel was subjected to analysis of the carbon contents, and asample of the spent regeneration solution was subjected to analysis forthe silicium contents. The results for day no 0 is the result (carboncontents) of the silica gel used for packing the columns. TABLE 6Assessment of column lifetime during prolonged flushing with typicalchromatographic eluents by measurement of remaining carbon and releasedsilicium. Measured Column Duration Measured C Si Volume Relative C no(days) (%) (mg) (mL) (%) Chrom solution 100 Å 0 19.40 0.00 0 100.00ODDMS 204614/15 20% EtOH 1 19.14 0.05 136 98.66 4.0 * 250 mm 204614/1620% EtOH 3 19.16 0.13 425 98.76 204614/17 20% EtOH 7 19.26 0.31 154099.28 204614/23 20% EtOH 12 19.28 0.25 1270 99.38 204614/24 20% EtOH 1619.27 0.41 1360 99.33 0 19.40 0.00 0 100.00 204614/18 Eluent 1 1 18.670.15 147 96.24 204614/20 Eluent 1 3 18.85 0.36 360 97.16 204614/21Eluent 1 7 18.76 0.87 870 96.70 204614/19 Eluent 1 12 18.64 1.33 132596.08 204614/22 Eluent 1 16 18.67 0.86 860 96.24 20% EtOH (% v/v) 200 Å0 9.80 0.00 0 100.00 ODDMS 204630/14 20% EtOH 1 9.61 0.03 160 98.064.0 * 250 mm 204630/13 20% EtOH 3 9.66 0.09 430 98.57 204630/15 20% EtOH7 9.72 0.09 425 99.18 204630/16 20% EtOH 12 9.69 0.18 610 98.88204630/18 20% EtOH 16 9.69 0.28 930 98.88 0 9.80 0.00 0 100.00 204630/19Eluent 2 1 9.55 0.13 125 97.45 204630/17 Eluent 2 3 9.55 0.40 400 97.45204630/20 Eluent 2 7 9.54 0.85 850 97.35 204630/21 Eluent 2 12 9.59 1.291290 97.86 204630/23 Eluent 2 16 9.49 0.70 700 96.84

Example 70

Column Life Time—Regeneration Solutions Comprising Formic Acid.

The life time of substituted silica gels may be limited by the chemicaldegradations of the gel by the solutions applied to the chromatographiccolumn, e.g. buffers and regeneration solutions. Chemical degradation ofsubstituted silica gels may be observed by the appearance of silicium inthe exit from the column, and by lowering of the carbon contents of thegel showing loss of the substitution. The following experiments show thesilicium appearance in column effluent and the decrease of the carboncontents of the gels during prolonged flushing with formic acidcontaining regeneration solutions. Thus, comparing to the situationusing chromatographic buffers or solvents, the formic acid containingregeneration solutions are not more deteriorating on the column matrix.

A batch of ODDMS silica gel was packed in five 4.0×250 mm steel columnsby standard procedure for packing chromatographic columns. Each columnwere then equilibrated with 3 CV 100% EtOH before continuous flushingwith formic acid was started. The five columns were then flushed with aregeneration solvent being formic acid (100% or 80%) for 1, 3, 7, 12,and 16 days, respectively. After the appropriate flushing time eachcolumn were then equilibrated with 3 CV of ethanol and the silica gelwas taken out of the columns. A sample of the spent silica gel wassubjected to analysis of the carbon contents, and a sample of the spentregeneration solution was subjected to analysis for the siliciumcontents. The results for day no 0 is the result (carbon contents) ofthe silica gel used for packing the columns. TABLE 7 Assessment ofcolumn lifetime during prolonged regeneration with solutions containingformic acid by measurement of remaining carbon and released silicium.Formic Measured Column acid Duration Measured C Si Volume Relative CColumn type no. (%) (days) (%) (mg) (mL) (%) 100 Å ODDMS 0 — 0 19.400.00 0 100.00 4.0 * 250 mm 204614/7 100 1 19.00 0.82 124 97.94 204614/5100 3 18.90 1.46 510 97.42 204614/6 100 7 19.26 1.95 620 99.28 204614/3100 12 18.97 5.63 1430 97.78 204614/2 100 12 18.94 3.92 1100 97.63 0 — 019.40 0.00 0 100.00 204614/8 80 1 19.08 1.67 177 98.35 204614/10 80 319.08 2.62 410 98.35 204614/9 80 7 18.93 4.55 970 97.58 204614/11 80 1217.04 6.07 1080 N.D. 204614/12 80 16 18.61 6.86 2090 95.93 200 Å ODDMS 0— 0 9.80 0.00 0 100.00 4.0 * 250 mm 204630/8 100 1 9.56 0.62 85 97.55204630/5 100 3 9.50 1.77 510 96.94 204630/6 100 7 9.41 1.02 800 96.02204630/3 100 12 9.67 1.31 1020 98.67 204630/2 100 12 9.63 1.22 165598.27 0 — 0 9.80 0.00 0 100.00 204630/7 80 1 9.64 0.56 141 98.37204630/10 80 3 9.42 0.77 440 96.12 204630/9 80 7 9.43 1.10 920 96.22204630/11 80 12 8.67 1.40 1470 N.D. 204630/12 80 16 9.18 1.46 2000 93.67

Example 71

Using Confocal Laser Scanning Microscopy Detecting Insulinfibrils onSource 30Q Anion Exchanger

Purpose

The purpose of using Confocal laser scanning microscopy is to visualdetermine how effectively different regenerating solvents are inremoving insulin fibrils from Source 30Q. With sophisticated imageprocessing software allowing the opportunity to measure the area ofinsulinfibrils on each picture giving a more precise judgment in steadof an visual judgment of each picture

The Confocal Principle

The principle in using CLSM is that the sample is stained with afluorescent dye. The stained sample is placed under the microscope andthe fluorescent dye is exitated using a laser. The emitted light comingfrom the fluorescent dye is detected and the image formed.

Confocal laser scannings microscope is as normal confocal microscopeusing a laser as ligthsource. The light from the laser is going throughthe objective of the microscope via the dichromatic beamsplitter. Thedichromatic beamsplitter is a device allowing the light from the laserto go through the objective down to the sample and the emitted lightcoming from the sample to pass the dichromatic beamsplitter and go up tothe photomultiplier tubes where the light is detected and the image isformed. Between the dichromatic beamsplitter and photomultipliertubes isthe confocal pinhole placed. The confocal pinhole works as a filterstopping all the light coming from out of focus regions in reaching thephotomultipliertubes. This means that the image there is formed comesfrom a very narrow focus plane. By adjusting the confocal pinhole it ispossible to move the image focus plane up and down through the sampleand produce a series of images along the optical (z) axis of themicroscope. This series of images can be collected into 3-D image of thesample.

Source 30Q

Source 30Q is a strong anion exchanger based on monodisperse beads witha particle size of 30 micron. The matrix consists of polystyrene/divinylbenzene. Source 30Q gives a weak autofluorescence's in the wavelengtharea above 650 nm. This means that is possible to see the Source 30Qparticles without any staining.

Thioflavin T

The dye used for staining insulin fibrils is Thioflavin T wich is knownfor staining amyloid proteins. Thioflavin T has a broad emissionspectrum with max emission ranging from below 490 nm and above 530 nm.This means that it is possible to distinct between light coming from theinsulinfibrils (green) and the autofluorescence's light coming from theparticles (red).

Method for Staining Insulinfibrils on Source 30Q

0.0385 g dry Source 30Q is put into 25-30 ml glass.

500 μl 96% ethanol is added to the Source 30Q

4.5 ml 0.05 M acetic acid adjusted to pH 3 with NaOH is added.

The mixture is mixed together by shaking the glass carefully

20 μl 116.62 mM Thioflavin T in Milli-Q-water is added

The mixture is carefully shaken for 5 min.

The sample is now stained and ready for analysing under the microscope

A small droplet of the mixture approximately 40 μl I placed in amicroscopic well and put in the microscope

10 2D pictures of each sample from different places of the well wastaken

Equipment

Microscopic conditions

Objective: 40*; oil; NA?

Laser: Argon 488 nm

Laser intensity: 100%

Confocal pinhole: 20 μm

Emission filter (No 2): 515/30M from Chroma

Emission filter (No 3): HQ650LP from Chroma

Microscope: Nikon TE300 equipped with PCM2000 confocal scanhead(photomultiplier) from Nikon.

Software: Nikon EZ2000 Viewer 2.5.77

Software used for image processing: AnalySIS 3.00

Image Processing

The area of insulinfibrils was measured on the 10 2D pictures fro eachsample. To ensure that each sample was treated exactly the same way theimage processing was done automatically by forming a macro. The macro isshown below. The area of each individual fibril from the 10 pictures ofeach sample was summarized in excel worksheet. The summarized fibrilarea from each sample was collected in a bar chart for comparison.

Macro for Measuring Area of Fibrils:

-   Op. Display=1;-   docActivate(“picture name”);-   DbLoadlmage( );-   MaximizeContrast( );-   ShadingCorrection(N*N average filter size; 3; lower limit; 1900;    upper limit; 2000);-   BinarzeColorImage(ColorThresholds:=NULL, Phase:=−1);-   Invert( );-   EdgeEnhance(size; 5; percent; 70);-   SetFrame(Left:=0, Top:=0, Right:=1023, Bottom:=1023);-   Detect( );-   ParticleResults( );-   Op.Display=6;-   Option. BurnOverlay=TRUE;-   SaveAs(FileName:);-   docActivate(“Sheet*”);-   SaveAs(FileName:);

Close(AskFor Save:=TRUE); TABLE 8 Measured area of fibrils on a spentSource 30Q gel before and after regeneration of the gel using differentregeneration solutions. Area of fibrils Regeneration solution (randomunits) None 485 None 458 NaOAc (0.25% w/w NaOAc, 0.24% w/w tris, 15442.5% w/w EtOH, pH 7.5 NaOH (1M) 101 HCOOH:water (50:50) 68 HCOOH (100%)0 HCOOH:EtOH (50:50) 0

Complete removal of the insulin fibrils are obtained using pure formicacid or a mixture of formic acid and ethanol. A 50:50 mixture of formicacid:water does not completely eliminate the fibrils, although thismixture is a more efficient regeneration solution than sodium hydroxide(1M).

Example 72

Standard procedure for regeneration of RP-HPLC columns with formic acidin production scale.

The procedures described below applies to two types of columns used infour chromatographic purification steps in a production scalepurification of human insulin.

Type 1 Column:

Bed height 32.5 cm

-   -   1. The column is flushed with approximately 1.5 CV 20% w/w        ethanol in water with a flow rate of 4.6 CV/h in order to remove        buffer salts    -   2. The flow direction in the column is reversed    -   3. The column is flushed with approximately 1.1 CV absolute        ethanol with a flow rate of 4.5 CV/h    -   4. 1.1 CV pure formic acid is pumped onto the column at a flow        rate of 2.1 CV/h    -   5. The flow is stopped and the column is allowed to stay with        formic acid for 30 minutes    -   6. The column is flushed with approximately 1.1 CV absolute        ethanol with a flow rate of 4.5 CV/h    -   7. The column is flushed with approximately 1.1 CV 20% w/w        ethanol in water with a flow rate of 4.5 CV/h    -   8. The flow direction in the column is switched back to normal    -   9. The column is equilibrated with minimum 4 CV of 20% w/w        ethanol in water with a flow rate of 4.6 CV/h        The column is now ready for use again.        Type 2 Column:        Bed height 37.5 cm    -   1. The column is flushed with approximately 1.5 CV 20% w/w        ethanol in water with a flow rate of 4.6 CV/h in order to remove        buffer salts    -   2. The flow direction in the column is reversed    -   3. The column is flushed with approximately 1.0 CV absolute        ethanol with a flow rate of 3.9 CV/h    -   4. 0.92 CV pure formic acid is pumped onto the column at a flow        rate of 1.9 CV/h    -   5. The flow is stopped and the column is allowed to stay with        formic acid for 30 minutes    -   6. The column is flushed with approximately 1.0 CV absolute        ethanol with a flow rate of 3.9 CV/h    -   7. The column is flushed with approximately 1.0 CV 20% w/w        ethanol in water with a flow rate of 3.9 CV/h    -   8. The flow direction in the column is switched back to normal    -   9. The column is equilibrated with minimum 4.0 CV of 20% w/w        ethanol in water with a flow rate of 4.6 CV/h        The column is now ready for use again.

On the Type 1 columns the regeneration with formic acid is carried outafter every 16^(th) run as a preventive action to stop build up ofcomponents, increasing column back pressures and increasing poolvolumes. By applying the regeneration procedure with formic acid in thechromatographic purification I step, the life time of the column bed isextended up to 2000 runs.

On the Type 2 columns regeneration with formic acid is carried outroutinely after every 60^(th) run or if increasing back pressures,increasing pool volumes and build up of impurities is observed. Byapplying the regeneration procedure with formic acid the life time ofthe column bed is extended up to 600 runs in chromatographicpurification III step and up to 900 runs in chromatographic step IV.

The column matrix used in chromatograhic purification I, III and IVsteps consists of octadecyidimethyl substituted silica particles (ODDMSsilica). The standard procedure described applies for all types ofsubstituted silica matrixes used in production scale.

The procedure is also used in formic acid regeneration procedures forcolumn matrices based on Source Q material

Examples of the effect at chromatographic purification III and IV areshown below. TABLE 9 Chromatographic purification III: Effect on poolvolume and back pressure. Back pressure (max. pressure over deliverypump) Before regeneration with formic acid (100%) Pool volume (weight)208 kg 27 Bar After regeneration with formic acid (100%) Pool volume 165kg 17 Bar

The regeneration reduces the pool volume with app. 21% and the backpressure with 37%.

FIG. 4A-B shows the effect of regeneration on preparative chromatogramfor Chromatographic purification III.

By applying the formic acid regeneration an improved separation andhuman insulin peak form is achieved (insulin peak being the large peakstarting at time 8.20 in upper figure and at time 14.02 in lowerfigure).

Example 73

Regeneration of DEAE Sepharose.

A batch of DEAE Sepharose which had been used for a large number ofpurification cycles in a process for purification of human growthhormone was regenerated by pure formic acid (100% HCOOH). Beforeregeneration the Sepharose has a brown colour indicating depositedmaterial on the gel. The regenerated Sepharose was much lighter incolour.

Samples of the regenerated Sepharose was compared to the Sepharosebefore regeneration using a colorimeter (Minolta CR-300) to quantify thecolour differences, cn.f. results in table 10. TABLE 10 Assessment ofthe regeneration of DEAE Sepharose when regenerated as a slurry with aregeneration solution of formic acid. Colour coordinates Sepharosematerial analysed L (light) A (red) b (yellow) Spent gel beforeregeneration 68.81 2.37 17.22 Spent gel after 3 hour regeneration 84.990.66 11.55 Spent gel after 24 hour regeneration 87.94 0.35 7.64 Spentgel after 24 hour regeneration 85.85 0.69 8.81 where fresh regenerationsolution has been applied at 12 hour. Unspent gel, i.e. which has never86.44 −0.06 2.01 been used for chromatography

Example 74

Regeneration of Spent Silica Gel Containing Glucagon Aggregates.

Glucagon and the glucagon-like peptides (GLP-1 and GLP-2) areparticularly susceptible to aggregation where they form fibrils, i.e.aggregates of β-sheet structures. In this example a model experiment wascarried out where human glucagon was loaded onto a silica column (asdescribed in examples 1-68). The glucagon solution was allowed to stayin the column for 3 days at 30° C. in order to introduce the pressureand performance problems mimicking the problems encountered during theindustrial manufacture of glucagon. The pressure over the column wasmeasured to 3.5 MPa using eluent 2 as described in example 69 at a flowrate of 9 mL/min at 22° C.

Following a regeneration cycle using formic acid (100%) the pressureover the column was reduced to 2.67 MPa illustrating the effectivenessof formic acid as a regeneration solution.

Example 75

Column Life Time—Regeneration Solution Containing 0.1 M NaOH and 60% w/wEthanol in Water.

The experiment was carried out as described in example 70 except for theregeneration solution which in this experiment was alkaline ethanol ascommonly used to regenerate chromatographic stationary phases.

The flow of regeneration solution was approximately 0.1 mL/min, and theexperiments were terminated after 4 days as the pressure over thecolumns were >10 MPa. The results until break down of the columns areshown in table 11. TABLE 11 Assessment of column life time duringprolonged regeneration with a regeneration solution containing 0.1M NaOHand 60% w/w ethanol in water. Meas- Meas- Rela- Dura- ured ured Vol-tive Column tion C Si ume C Column type no. (days) (%) (mg) (mL) (%) 200Å ODDMS 0 0 9.80 0.0 0 100 4.0 * 250 mm 204630/26 1 9.80 16.2 116 100204630/25 2 9.77 27.0 180 99.7 204630/24 4 9.59 31.9 228 97.9

Example 76

Regeneration of XAD 1180

The lifetime of the reverse phase polymeric resin XAD 1180 used forconcentrating of an insulin precursor from clarified fermentation brothwas limited because of severe accumulation of hydrophobic contaminantssuch as colored compounds, peptides and antifoams from the fermentation.The normal regeneration cycle was based on washing with a regenerationsolution containing 80% Ethanol in 0.1M citric acid, pH 3.0 followed byheating with a 5% NaOH solution at 80° C. This regeneration process wasnot efficient to remove accumulated contaminants.

Removal of bound antifoam (Pluronic PE 6100 and P2000) from spent resinwas evaluated by experiments with different concentration and contactingtime of ethanol and isopropanol in static mode and compared to a formicacid regeneration (Table 12). The formic acid treatment is superior inremoving the adsorbed contaminants compared to standard industrialregeneration solvents. TABLE 12 Efficiency of different regenerationsolutions in removing adsorbed antifoam contaminants from a spent XAD1180 chromatographic stationary phase. Conc. Regeneration Time Temp. ofantifoam on solvent Conc. (hours) (° C.) resin (ppm) Ethanol 84% 2 2520023 Ethanol 92% 2 25 13058 Ethanol 99% 2 25 8042 Ethanol 84% 6 2525083 Ethanol 84% 2 50 14712 Ethanol 99% 6 50 9911 Isopropanol 70% 2 2515899 Isopropanol 99% 2 25 3262 Formic acid 99% 2 25 670

1. A process for regenerating a chromatographic stationary phase whereinsaid chromatographic stationary phase is contacted with a regenerationsolution comprising at least one organic acid and less than about 75%w/w water.
 2. The process according to claim 1, wherein the regenerationsolution comprises at least one organic acid and less than about 1% w/wwater.
 3. The process according to claim 1, wherein the concentration ofsaid organic acid is at least about 25% w/w.
 4. The process according toclaim 1, wherein said organic acid is formic acid.
 5. The processaccording to claim 1, wherein said organic acid is acetic acid.
 6. Theprocess according to claim 1, wherein said regeneration solutioncomprises an organic solvent.
 7. The process according to claim 6,wherein said organic solvent is ethanol.
 8. The process according toclaim 6, wherein said organic solvent is 2-propanol.
 9. The processaccording to claim 6, wherein said organic solvent is acetonitrile. 10.The process according to claim 6, wherein said organic solvent isselected from the group consisting of methanol, 1-propanol, and hexyleneglycol.
 11. The process according to claim 1, wherein said regenerationsolution contains less than 0.5% water.
 13. The process according toclaim 1, wherein said chromatographic stationary phase is contacted withsaid regeneration solution inside the chromatographic column.
 14. Theprocess according to claim 13, wherein said chromatographic stationaryphase is regenerated without repacking the column.
 15. The processaccording to claim 13, wherein said chromatographic stationary phase isfluidized during said regeneration.
 16. The process according to claim13, wherein the chromatographic eluent or equilibrium buffer isdisplaced by a water miscible organic solvent before saidchromatographic stationary phase is contacted with said regenerationsolution.
 17. The process according to claim 16, wherein said organicsolvent is also present in the chromatographic eluent or equilibriumbuffer.
 18. The process according to claim 16, wherein said watermiscible organic solvent is also present in the regeneration solution.19. The process according to claim 1, wherein said chromatographicstationary phase is contacted with said regeneration solution outsidethe chromatographic column.
 20. The process according to claim 1,wherein said chromatographic stationary phase is a RP-HPLC matrix. 21.The process according to claim 1, wherein said chromatographicstationary phase is a silica or substituted silica material.
 22. Theprocess according to claim 21, wherein said chromatographic stationaryphase is C16 or C18 substituted silica.
 23. The process according toclaim 21, wherein said chromatographic stationary phase is C4, C8 orphenyl-substituted silica.
 24. The process according to claim 21,wherein said chromatographic stationary phase is a polymeric material.25. The process according to claim 1, wherein said chromatographicstationary phase is contacted with said regeneration solution for atleast 1 minute.
 26. The process according to claim 1, wherein saidchromatographic stationary phase is contacted with said regenerationsolution until the pressure drop over the length of the chromatographiccolumn at normal flow rate decreases by at least 10%.
 27. The processaccording to claim 1, wherein contacting of said chromatographicstationary phase with said regeneration solution is performed at atemperature in the range from about 5° C. to 50° C.
 28. The processaccording to claim 1, wherein the life time of said chromatographicstationary phase is at least 500 chromatographic cycles.
 29. The processaccording to claim 1, wherein said process is applied to saidchromatographic stationary phase for every chromatographic cycle. 30.The process according to claim 1, wherein said process is applied tosaid chromatographic stationary phase at least once every 100chromatographic cycles.
 31. A process for the production of atherapeutic polypeptide or a precursor thereof comprising at least onechromatographic step wherein the chromatographic stationary phase isregenerated by a process according to claim
 1. 32. The process accordingto claim 31, wherein said therapeutic polypeptide is a derivativecomprising a lipophilic substituent.
 33. The process according to claim31, wherein said therapeutic polypeptide is selected from the groupconsisting of glucagon, glucagon-like peptide 1, glucagon-like peptide2, exendin-4, TFF peptides, human insulin, analogues thereof andderivatives thereof.
 34. The process according to claim 31, wherein saidpolypeptide or a precursor thereof is selected from the group consistingof Lys²⁶(N^(ε)-(γ-Glu(N^(α)-hexadecanoyl)))-GLP-1(7-37),Arg³⁴-GLP-1(7-37), exendin-4, Lys¹⁷Arg³⁰-GLP-2(1-33),Arg³⁰Lys¹⁷N^(ε)(β-Ala(N^(α)-hexadecanoyl)) GLP-2(1-33) andGly²-GLP-2(1-33).
 35. The process according to claim 31, wherein saidpolypeptide or a precursor thereof is selected from the group consistingof threonine methyl ester^(B30) human insulin, threonine ethylester^(b30) human insulin, Asp^(B28) human insulin, threonine methylester^(B30) Asp^(B28) human insulin, threonine ethyl ester^(B30)Asp^(B28) human insulin, Lys^(B28) Pro^(B29) human insulin,Met^(B-1)Arg^(B0)Lys^(B28) Pro^(B29) human proinsulin, Lys^(B3)Glu^(B29) human insulin, Gly^(A21) Arg^(B31)Arg^(B32) human insulin,des(B30) human insulin, N^(εB29)-tetradecanoyl des(B30) human insulin,N^(εB29)-litocholoyl-γ-glutamyl des(B30) human insulin,N^(εB29)-octanoyl des(B30) human insulin, and. N^(εB29)-octanoyl humaninsulin.
 36. A chromatographic stationary phase which has beenregenerated by contacting said chromatographic stationary phase with aregeneration solution comprising at least one organic acid and less thanabout 75% w/w water.
 37. The chromatographic stationary phase accordingto claim 36, wherein said chromatographic stationary phase has beenregenerated by contacting said chromatographic stationary phase with aregeneration solution comprising at least one organic acid and less thanabout 1% w/w water.
 38. The chromatographic stationary phase accordingto claim 36, wherein said chromatographic stationary phase is a silicaor a substituted silica material.
 39. A polypeptide product manufacturedby a process comprising the steps of a) purifying a polypeptide or aprecursor thereof using the chromatographic stationary phase accordingto claim 36, and b) isolating said polypeptide or a precursor thereof togive the resulting polypeptide product.
 40. A polypeptide productmanufactured by a process wherein is used a chromatographic stationaryphase according to claim
 36. 41. An automated chromatographic equipmentcomprising piping and control system for implementing the processaccording to claim
 1. 42. A pharmaceutical composition prepared by aprocess comprising the steps of a) first purifying a polypeptide or aprecursor thereof using a chromatographic stationary phase regeneratedby the process according to claim 1, b) then drying said polypeptide,and c) finally admixing with a pharmaceutically acceptable excipient.43. A pharmaceutical composition prepared by a process comprising thesteps of a) first purifying a polypeptide or a precursor thereof using achromatographic stationary phase regenerated by the process according toclaim 11, b) then drying said polypeptide, and c) finally admixing witha pharmaceutically acceptable excipient.